Plugs and closures

ABSTRACT

Cam-operated plugs or closures for use strut-like members the closing of openings in the fuel element stack pipes of atomic reactors. The plugs have a plurality of locking members mounted on the plug body, which locking members are pivotable by movement of a cam arrangement to a locking position in which they project beyond the periphery of the plug to engage the wall of the opening to prevent the plug from being withdrawn from the opening. The locking members comprise strut-like members which are arranged so that a force applied to the locking members by a tendency to withdraw the plug from the opening is a substantially compressive force.

United States Patent West 451 Apr. 4, 1972 PLUGS AND CLOSURES DerekWest, Dorset, England Flight Refueling Limited, London, England [22]Filed: Feb. 28, 1969 [21] Appl.N0.: 803,338

[72] Inventor:

[73] Assignee:

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220/55 M; 176/30, 31, 79, so

3,157,579 11/1964 Hummel ..176/30 Primary Examiner-Laverne D. GeigerAssistant Examiner-Richard J. Sher Attorney-Arthur B. Colvin [57]ABSTRACT Cam-operated plugs or closures for use strut-like members theclosing of openings in the fuel element stack pipes of atomic reactors.The plugs have a plurality of locking members mounted on the plug body,which locking members are pivotable by movement of a cam arrangement toa locking position in which they project beyond the periphery of theplug to engage the wall of the opening to prevent the plug from beingwithdrawn from the opening. The locking members comprise strut-likemembers which are arranged so that a force applied to the lockingmembers by a tendency to withdraw the plug from the opening is asubstantially compressive force.

1 1 Claims, 3 Drawing Figures Patented April 4, 1972 5 Sheets-Shoot 1 Da x a We. 57

/NVENTOR AHTHUR OD'LWN ATTORNEY Patented April 4, 1972 3 Sheets-Sheet 2pirhsw as IN VE N TOR Y I B ARTHUR ATTORNEY Patented April 4, 19723,653,410

3 Sheets-Sheet 5 DER a K W! s7 INVENTOR A UR OlkV/A/ ATTORNEY PLUGS ANDCLOSURES This invention relates to plugs or closures for closingopenings such as the bores of conduits, orifices and the like. The termplugs is intended to include not only members which themselves whollyblock the openings in which they are mounted, but also members which,when located in said openings, provide a closable opening of smallerdiameter than the diameter ofthe opening.

Such plugs are, in some applications, required to withstand highpressures tending to force them out of the openings which they serve toclose. One particular example of their use is in the fuel element stackpipes of atomic reactors where, particularly in advanced gas cooledreactors in which the fuel elements are attached directly to the plugs,the blowing out of one of the plugs would result in a very dangeroussituation due to' thc'release, not only of hot gases, but also of radioactive material.

It is therefore the object of the present invention to provide a plughaving positive locking means for retaining it in position.

According to the present invention there is provided a plug including abody adapted to make a fluid tight joint with a peripheral surface onthe wall of a member surrounding the said plug, locking means comprisinga plurality of locking members pivotally mounted on the plug body, thelocking members being pivotable by cam means between a retractedposition and a locking position in which locking position the lockingmembers project laterally outwardly beyond the periphery of the plug toengage with abutments in the said wall facing towards the inner end ofthe plug to prevent the plug from being withdrawn from the member.

The locking members preferably comprise strut-like members which, whenin the locking position, are inclined outwardly towards the outer endface of the plug to engage said abutments, the arrangement being suchthat a force applied to the locking members by a tendency of the plug towithdraw from the opening is a substantially compressive force.

The cam means may comprise a cam ring movable relative to the plug body,the locking members each having a cam follower engageable in a cam slotin said cam ring, movement of the ring relative to the body causing thecam followers to move along the cam slots to thereby cause the lockingmembers to be moved between their retracted and locking positions. Thecam ring may be rotatably mounted in the body or may be axially slidabletherein. The cam ring may be provided with abutment surfaces which, whenthe locking members are in their locking positions are engaged therebythe said abutment surfaces being so arranged that a force applied tothem by the locking members, due to a tendency of the said lockingmembers to move towards their retracted position, has no componentacting in a direction to move the cam ring to retract the lockingmembers.

Subsidiary locking means may be provided to prevent relative movement ofthe cam ring and the body when the main locking members are in theirlocking position, the subsidiary locking means being released byengagement with the plug of a grab or other manipulating device capableof moving the cam ring and removing the plug from the opening.Altematively, or in addition, a subsidiary locking device may beprovided, the release of which is accompanied by the operation of meansfor equalising the pressure on both sides of the plug so that the lattercannot be unlocked whilst there is a pressure difference across theplug.

Two embodiments of the invention will now be described, by way ofexample only, with reference to the accompanying drawings in which:

FIG. 1 shows a sectioned view of a plug having a rotary cam ring.

FIG. 2 shows a section plan view of the plug shown in FIG. 1.

FIG. 3 shows a sectionalized view ofa plug in which the cam ring slidesaxiallyv Referring now to FIG. 1 the plug 1 closes the opening in aconduit 2. The plug has a main body 3 of circular cross section, theperipheral surface of which is stepped so that the outer portion 4 is ofsmaller diameter than the inner portion 5. The inner portion 5 of theplug fits relatively closely in the opening and has therein annulargrooves 6 and 7 to receive respectively sealing rings 8 and 9 whichengage the wall of the conduit to provide a fluid-tight seal. The inwardmovement of the plug is limited by a chamfered abutment 10 on the wallof the conduit which engages with an annular chamfered portion 11 of theplug.

Five part-circular grooves 12 are equally spaced around the plug on theshoulder 13 formed between the greater and smaller diameters of the plugbody 3. The grooves 12 are each tangential to a circle about the plugaxis 14. Part-cylindrical ends 18 of locking members 15 are located ineach of the grooves 12 and are retained therein by a ring 16 locatedabout the smaller diameter portion 4. The locking members 15 are locatedin recesses 17 in the ring 16, the members 15 having trunnions co-axialwith the part cylindrical ends 18 constrained by the ring 16 to retainthe locking members in the part circular grooves 12. The locking membersare thus retained in engagement with the plug whilst being free to pivotabout the axis 18 of the part circular grooves 12. The locking members15 have, formed integrally therewith, cam pegs 19 which are engaged in acam slot 20 formed in a cam ring 21.

The locking members 15 are of strut-like configuration and haveshoulders 24 which, when the locking members are moved to the lockingposition, engage with abutments 25 on the wall of the conduit. Theabutments 25 may be a series of individual abutments, each associatedwith a corresponding one of the locking members, or may be acircumferential recess machined in the wall of the conduit. Theabutments 25 face towards the inner end of the plug so that when theshoulders 24 engage the abutments 25, the plug cannot be removed fromthe conduit. The arrangement is such that a force applied to the lockingmembers 15 by a tendency of the plug to withdraw from the opening is asubstantially compressive force.

As shown in FIG. 2, the cam slot is a substantially annular slot of 5equal segments each associated with one of the locking members 15. Eachcam segment has a first radiussed portion 22 which extends about aradius struck from the axis 14 and a second portion 23 which is astraight part of the slot interconnecting the portion 22 with theportion 22 of adjacent cam segment. The center section of the portion 23is thus at a smaller distance from the center of the ring than theportion 22. Thus, when the cam pegs 19 of the locking members 15 arelocated in the portions 22 the locking members are in the outer, orlocking, position as shown on the left-hand side of FIG. 1 while whenthe cam pegs 19 are in the center section of portions 23 the lockingmembers 15 are in the retracted position as shown on the right-hand sideof FIG. 1. When the locking members 15 are in the retracted positionthey are contained within the periphery of the plug to thereby enablethe plug to be withdrawn from the opening in the conduit.

Reaction pins 48 are secured to the cam ring 21 adjacent each of theportions 22 of the cam slot 20. The axis of each of the pins 48 isparallel to the longitudinal axis 14 of the plug. The pins 48 are sopositioned that when the locking members 15 are in the locking position,the pins 48 are adjacent the main body of the locking members and liftthe cam pegs l9 slightly clear of the surface of the cam slot. Thus aforce applied to the locking members radially inwardly due to a tendencyof the locking members to move towards their retracted position isapplied against the pins 48, and thus there is no component acting onthe cam pegs 19 to rotate the cam ring 21 or to apply an excessive loadon the cam pegs l9.

Rotational movement of the cam ring 21 is limited to approximately 45 bya pin 26 carried by the rotatable ring 21, which pin 26 projectsradially inwardly from the cam ring into a part circumferential slot 27in the main body 3. Subsidiary locking means co-operable with the pin 26is provided by a valve arrangement 28 mounted in a stepped bore 29extending through the main body 3. The valve arrangement has a valvestem 30 carrying a valve seal 31 which is biassed into engagement with avalve seat 32 on the body 3 by a coil compression spring 33 to provide afluid tight seal. The stem 30 of the valve projects axially from theouter face of the plug body 3 and has an axial passage 34 extending fromits outer end to a diametrical bore 35 adjacent the round seat 32 sothat when the closure member 30 is displaced in an axially inwarddirection, a fluid passage is provided through the plug. The stem 30 isstepped to provide smaller and larger diameter portions thereof and,when the valve seal 31 is seated on the valve seat 32 the largerdiameter portion 36 of the valve stem 30 projects into the partcircumferential slot 27 in the plug and, by obstructing movement of thepin 26 carried by the cam ring 21, prevents the cam ring 21 from beingrotated to retract the locking members. Axial inward movement of thevalve stem to unseat the valve seal 31 brings the smaller diameterportion 37 of the valve stem into register with the slot 27, thusremoving the obstruction to the rotation of the cam ring 21.

The cam ring 21 extends axially outwardly beyond the plug body 3, beingretained thereon by a stop ring 38 secured to the body 3 at itsperiphery and engaging with shoulder 39 on the cam ring 21 to locate thecam ring relative to the body. The axially projecting portion of the camring 21 is formed with a plurality of longitudinal slots 40, only one ofwhich is shown, in each of which is pivotally mounted, about an axis 41tangential to the axis 14 of the plug, a two-armed locking lever 42. Thelower arm 43 of the lever 42 is normally engaged with a notch 44 in thestop ring 38, the arm being urged into the notch by a torsion spring 45located about the axis 41. When the lever 42 is in this position, aroller 46 mounted on the upper arm 47 projects radially outwardly beyondthe periphery of the cam ring 21.

The plug is intended to be manipulated for insertion and removal fromthe opening in the conduit by a charge machine which is not illustrated.The charge machine includes a grab device which engages with, and islatched onto, the cam ring 21. The grab device also includes an outersleeve which fits over the axially projecting portion of the cam ring21, and an inner sleeve which passes within the said projecting portion.

Thus, when the charge machine is coupled to the plug, the outer sleevethereof engages the rollers 46 on the upper levers of the locking lever42 to withdraw the arms 43 from the notches 44 in the stop ring 38. Theinner sleeve of the grab device engages the axially projecting end ofthe valve stem 30 and moves it to unseat the valve seal 31 from the seat32 to thereby remove the obstruction from the path of the pin 26 on thecam ring 21 so that the cam ring can be turned by the grab to retractthe locking members.

Thus, rotation of the cam ring to release the locking members can takeplace only if the grab device is properly coupled to the plug and theinterior of the conduit is in communication with the charge machine sothat the pressures on both sides of the plug are equalized.

Referring now to the alternative embodiment illustrated in FIG. 3 thisembodiment is similar to that described with reference to the FIGS. 1and 2 and like parts will have like reference numerals.

The plug has a main body 3 of circular cross section the peripheralsurface of which is stepped as described previously to have an upper,outer, portion of smaller diameter and a lower or inner portion oflarger diameter. As before the locking members are located in partcircular grooves 12, but in this embodiment, the locking members areretained in the grooves by locating pins 50 secured to the main body 3of the plug, the outer ends of the pins lying adjacent each side of thelocking members 15 and engaging the trunnions 51 formed on either sideof the locking members 15 so that the locking members 15 are retained inengagement with the grooves 12 in the plug while being free for pivotalmovement about the axis 18.

The locking members 15 extend towards the outer end of the plug and eachcarries, at its outer end, a pair of co-axial trunnions which form a campeg 52, the axis of which is paral lel to the pivot axis 18. A camsleeve 53 is slidable on the smaller diameter portion 4 of the body ofthe plug, the cam sleeve comprising an inner sleeve 54 having on itsinner end a plurality of flat faces 55 tangential to a circle about theaxis 14 each face being associated with a corresponding one of the pegs52 on the locking members 15, An outer sleeve member has thereon aplurality of inclined flat faces 57 each spaced from, and substantiallyparallel to, the inclined faces on the inner sleeve 54 to form a camslot. A longitudinal slot 58 is formed in the center of each of theinclined faces 57, the slots being adapted to receive and locate alocking member 15. The pegs 52 on each of the locking members extendinto the spaces formed between the inclined faces 55 and 57.

When the cam sleeve 53 is in its upper or outermost position as shown onthe right-hand side of FIG. 3, the pegs 52 lie at the lower ends of thethus formed cam slots and the locking members 15 are therefore held inretracted positions by the faces 55 and 57. Inward or downward movementas viewed in the drawing, of the cam sleeve 53 causes the pegs 52 toride up the faces on the cam sleeve 53, thus pivoting the lockingmembers 15 outwardly towards their locking positions, the final part ofthe inward movement of the cam sleeve 53 bringing the pegs 52 oppositeto the flat portion of the face 55 on the cam sleeve 53 so that aradially inwardly directed force acting thereon due to a tendency of thelocking members to move towards their retracted position, isperpendicular to the flat faces has no component tending to urge thesleeve outwardly, and the locking members are positively locked in thelocked position, The locking members 15 are shown in the locked positionon the left-hand side of FIG. 3. Conversely, outward movement of the camsleeve 53 causes the locking members to be retracted by co-operation ofthe pegs 52 with the faces 55 and 57.

Subsidiary locking means is provided which, as described with referenceto the embodiment shown in FIGS. 1 and 2 prevents the locking members 15from being retracted until the pressure on both the inner and outersides of the plug is equalized.

Accordingly, a valve arrangement 28 similar to that described withreference to FIG. 1 is incorporated, the valve stem 30 having a smallerdiameter portion 37 and a larger diameter portion 36 as describedpreviously. The locking device comprises a ball 58 contained in a bore59 which communicates between the stepped bore 29 and the outerperipheral surface of the main body 3 on which the cam sleeve isslidable. The cam sleeve 53 has a chamfer 60 on its upper innerperipheral edge. The ball 58 is urged by the larger diameter portion 36of the valve stem 30 to a position in which it projects beyond theperipheral surface of the main body 3 as shown in FIG. 3. Thus, when thecam sleeve is in the innermost position and the locking members 15 arein the locked position the ball 58 is jammed between the chamfer 60 andthe larger diameter portion 36 of the valve stem 30 so that the camsleeve cannot be moved to its outermost position to enable the lockingmembers to be retracted.

Movement of the cam sleeve 53 is controlled by a control ring 62 whichis axially slidable in an outer ring 63 secured to the body 3 of theplug through an attachment plate 64. The cam sleeve 53 is connected tothe control ring 62 by volts which extend through orifices in the plate64 and is maintained in correct positional relationship thereto bytubular distance pieces 61, through which the bolts pass. The lower faceof the attachment plate 64 provides a stop to limit the outward movementof the cam sleeve 53. The inward movement of the cam sleeve 53 islimited by the pegs 52 abutting the top of the cam slot formed betweenthe two faces 55 and 57.

Further locking means may be provided by a locking pin 65 to positivelylock the control ring 62 to the outer ring 63 when the locking members15 are in the locking position. Thus when the control ring 62 is in itsinnermost position an orifice therein is aligned with an orifice in theouter ring 63. The locking pin may then be passed through both thecontrol ring and the outer ring until a head 67 on the locking pin abutsthe inner face of the control ring 62 and may be secured in thisposition by a padlock 66, the hasp of which passes through a bore in theshank of the locking pin 65.

As with the previous embodiment, the plug is intended to be manipulatedfor insertion and removal from the opening in the conduit by a chargemachine. Before the charge machine can be secured to the plug thelocking pin 65 and padlock 66 must be removed. The charge machine forthis embodiment does not need the outer sleeve described previously.Thus, when the charge machine is coupled to the plug, the inner sleeveof the grab device engages the axially projecting end ofthe valve stem30 and moves it to unseat the valve seal 31 from the seat 2 which movesthe larger diameter portion 36 of the valve stem from the orifice 59.The control ring 62 may then be moved outwardly by the grab device theball 58 being urged into the orifice 59 by the chamfer 60 on the camsleeve 63 so that the cam sleeve may then be moved to its outermostposition to retract the locking members to the position shown on theright-hand side of FIG. 3 when the plug may be withdrawn from theopening. Thus, as in the previous embodiment, the plug may be removedonly if the grab device is properly coupled to the plug and the interiorof the conduit is in communication with the charge machine so that thepressures on both sides ofthe plug are equalized.

It will be understood that the charge machine will be so interlockedwith the plug that it cannot be disengaged from the plug until thelatter is securely locked in position in the opening, but theinterlocking means for this purpose form no part of the presentinvention.

lclaim:

l. A plug including a body having an inner end adapted to make a fluidtight joint with a peripheral surface on the wall of a membersurrounding the said plug, said wall having abutmerits axially spacedoutwardly from the inner end of said plug, locking means comprising aplurality of locking members pivotally mounted on the plug body, cammeans operatively engaging said locking members, said cam meanscomprising a cam ring movable relative to the plug body, said cam ringhaving cam slots, the locking members each having a cam followerengageable in a cam slot in the cam ring, movement of the ring relativeto the body causing each of the cam followers to move along theassociated cam slot to thereby pivot the locking members between aretracted position and a locking position, in which locking position thelocking members project laterally outwardly beyond the periphery of theplug to engage said abutments in the said wall to prevent the plug frombeing withdrawn from the member.

2. The combination set forth in claim 1 in which the locking memberscomprise strut-like members each having a locking shoulder, said lockingshoulders when the locking members are in the locking positionprojecting laterally outwardly to engage said abutments, the arrangementbeing such that a force applied to the locking members by the tendencyof the plug to withdraw from the opening is a substantially compressiveforce.

3. A plug as claimed in claim 1 in which the cam ring is rotatablymovable relative to the body.

4. A plug as claimed in claim 1 in which the cam ring is slidableaxially relative to the plug body.

5. A plug as claimed in claim 1 in which the cam ring is provided withabutment means which, when the locking members are in their lockingpositions, are engaged thereby, the said abutment means being soarranged that a force applied to said means by the locking members, dueto a tendency of the said locking members to move towards theirretracted position, has no component acting in a direction to move thecam ring to retract the locking members.

6. A plug as claimed in claim 1 in which subsidiary locking means isprovided carried by said cam ring and operativel engaging said plug bodyto prevent relattve movement 0 the cam ring and the plug body when themain locking members are in their locking position. 7

7. A plug as claimed in claim 6 in which the cam ring has a notchtherein, the subsidiary locking means comprises at least one leverincluding a locking portion and a release portion, means normallybiasing said lever to a locking position in which the locking portion isengaged with said notch to thereby prevent the said relative movement,said locking portion being movable to a release position when saidrelease por tion is actuated.

8. A plug as claimed in claim 1 in which an additional locking device isprovided to prevent relative rotation of said cam ring and plug body,said locking device comprising an abutment member carried by said camring and a locking member movable into the path of said abutment memberto restrain rotation of said cam ring, and means normally retaining saidlocking member in the path of movement of said abutment member.

9. A plug as claimed in claim 8 in which the plug body has a passagewaytherethrough parallel to the axis thereof, said passageway having avalve seat near its inner end, the locking member comprises a valve stemslidably mounted in said passageway, said stem having a valve member atone end, means resiliently urging to said stem outwardly to retain saidvalve member against said seat to restrain flow of fluid through saidpassageway and to retain said locking member in locking position withrespect to said abutment member to restrain rotation ofsaid cam ring.

10. A plug as claimed in claim 9 in which the valve stem has steppedlarger and smaller diameter portions, the larger diameter portion, whenthe locking member is in locking position being in the path of movementof said abutment member to restrain rotation of said cam ring, movementof the locking member to an open position moving the smaller diameterportion of the valve stem into register with the abutment member tothereby permit rotation of said cam ring.

11. A plug as claimed in claim 9 in which said valve stem has apassageway therethrough, said passageway being closed when said valvemember is retained against said seat, thereby preventing equalization ofthe pressure on both sides of the plug to prevent movement of thelocking member away from said abutment member so long as there is apressure difference across the plug.

1. A plug including a body having an inner end adapted to make a fluidtight joint with a peripheral surface on the wall of a membersurrounding the said plug, said wall having abutments axially spacedoutwardly from the inner end of said plug, locking means comprising aplurality of locking members pivotally mounted on the plug body, cammeans operatively engaging said locking members, said cam meanscomprising a cam ring movable relative to the plug body, said cam ringhaving cam slots, the locking members each having a cam followerengageable in a cam slot in the cam ring, movement of the ring relativeto the body causing each of the cam followers to move along theassociated cam slot to thereby pivot the locking members between aretracted position and a locking position, in which locking position thelocking members project laterally outwardly beyond the periphery of theplug to engage said abutments in the said wall to prevent the plug frombeing withdrawn from the member.
 2. The combination set forth in claim 1in which the locking members comprise strut-like members each having alocking shoulder, said locking shoulders when the locking members are inthe locking position projecting laterally outwardly to engage saidabutments, the arrangement being such that a force applied to thelocking members by the tendency of the plug to withdraw from the openingis a substantially compressive force.
 3. A plug as claimed in claim 1 inwhich the cam ring is rotatably movable relative to the body.
 4. A plugas claimed in claim 1 in which the cam ring is slidable axially relativeto the plug body.
 5. A plug as claimed in claim 1 in which the cam ringis provided with abutment means which, when the locking members are intheir locking positions, are engaged thereby, the said abutment meansbeing so arranged that a force applied to said means by the lockingmembers, due to a tendency of the said locking members to move towardstheir retracted position, has no component acting in a direction to movethe cam ring to retract the locking members.
 6. A plug as claimed inclaim 1 in which subsidiary locking means is provided carried by saidcam ring and operatively engaging said plug body to prevent relativemovement of the cam ring and the plug body when the main locking membersare in their locking position.
 7. A plug as claimed in claim 6 in whichthe cam ring has a notch therein, the subsidiary locking means comprisesat least one lever including a locking portion and a release portion,means normally biasing said lever to a locking position in which thelocking portion is engaged with said notch to thereby prevent the saidrelative movement, said locking portion being movable to a releaseposition when said release portion is actuated.
 8. A plug as claimed inclaim 1 in which an additional locking device is provided to preventrelative rotation of said cam ring and plug body, said locking devicecomprising an abutment member carried by said cam ring and a lockingmember movable into the path of said abutment member to restrainrotation of said cam ring, and means normally retaining said lockingmember in the path of movement of said abutment member.
 9. A plug asclaimed in claim 8 in which the plug body has a passageway therethroughparallel to the axis thereof, said passageway having a valve seat nearits inner end, the locking member comprises a valve stem slidablymounted in said passageway, said stem having a valve member at one end,means resiliently urging to said stem outwardly to retain said valvemember against said seat to restrain flow of fluid through saidpassageway and to retain said locking member in locking position withrespect to said abutment member to restrain rotation of said cam ring.10. A plug as claimed in claim 9 in which the valve stem has steppedlarger and smaller diameter portions, the larger diameter portion, whenthe locking member is in locking position being in the path of movementof said abutment member to restrain rotation of said cam ring, movementof the locking member to an open position moving the smaller diameterportion of the valve stem into register with the abutment member tothereby permit rotation of said cam ring.
 11. A plug as claimed in claim9 in which said valve stem has a passageway therethrough, saidpassageway being closed when saId valve member is retained against saidseat, thereby preventing equalization of the pressure on both sides ofthe plug to prevent movement of the locking member away from saidabutment member so long as there is a pressure difference across theplug.